The best way to get rid of black snakes and copperheads around your home and yard is to keep them from wanting to come there in the first place. Killing snakes won't do any good unless you address the reasons why they found your home attractive to begin with. Copperheads and black snakes are woodland snakes that live in underbrush. While black snakes are harmless to humans, copperheads are venomous. Their bites are rarely fatal, but they do require medical attention. If you remove their food sources and eliminate areas in and around your house where snakes can hide, they will keep looking rather than settling in to stay.
Seal any ground-level openings around your home. Securely cover vents and patch holes in screens. Secure openings around pipes with caulk or expanding foam.
Remove brush piles and rock piles. Trim long grass, and clear out underbrush from your yard. Snakes prefer to hide in cool, dark areas.
Control rodents and remove their food sources. Snakes eat mice and rats, so eliminating them keep snakes away.